A Response Surface Approach for Determining Optimal Mix Parameters for Normal Strength Concrete

The study evaluates the influence of water/cement ratios and aggregates contents on the engineering properties of normal weight concrete. Response Surface Methodology (RSM) using historical design was adopted to design and develop predictive models and perform the optimization of concrete prepared with cement, fine aggregate (FA), coarse aggregate (CA) contents at different water/cement ratio (W/C) by volume. Concrete mixes were prepared using fixed content of ordinary Portland cement and the different mixtures. The density and compressive strength of hardened concrete specimens were determined at the curing 28 days. The response surface analysis showed that W/C and aggregate contents have significant effects on density and compressive strength of concrete. The regression model yielded good correlations with the experimental data. The optimized density and 28-day compressive strength values of 2522.973 kg/m3 and 29.977 N/mm2 were achieved for the concrete mix containing 1.5-part of FA, 3-part of CA and 0.60 W/C, respectively. The optimal concrete mix parameters determined using RSM provides the basis for selecting appropriate safe concrete component ratios.